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New Transport Approach

With never-ending advances in technology and tumbling prices, I wonder if any high-end audio CD player manufacturer is considering an approach such as this - populate the player with 700 megabytes of RAM and pre-read the whole CD into RAM. We know this is completely reliable (or else our beloved MS Office wouldn't work). Then the whole transport system could be shut down, eliminating any concerns about mechanical or electrical noise, and the "CD" could be played back straight from RAM through the DAC. It would seem like this would reduce or eliminate jitter completely. There would be an "initialization" time penalty, but I would think for the high-end market, that wouldn't be a huge deal. Any thoughts? -Kirk
kthomas
jfrech's avatar
jfrech
1,816 posts
 
Doesn't Meridian do some of this today in their new cd players? They don't load the whole disk in, but enough to read the data out of memory to eleminate the jitter issues...
kthomas OP
911 posts
 
You can buy 256Mb RAM SIMMs for $140 or so apiece - since you'd need three, the maximum cost would be $420, but I'm sure the wholesale bulk cost would be decidedly less. At this point, it would be a definite cost addition to the machine, non-trivial to the point that it would only be appropriate for a high-end player.

However, I would think that it would eliminate a lot of cost associated with a high-quality transport section. I don't know much about what goes into making a high-end transport high-end, but I'm sure there's significant parts cost associated with it. Since you'd be separating the reading of the disc from the playback of the music, you wouldn't need all physical separation, so maybe at the end of the day it wouldn't be that much of an uptick in parts cost. Maybe it would ultimately cost less

I think most high-end players use one form of buffering or another towards the same goals, but the advantage I see here is buffering the whole disc, since that is what allows you to shut down the transport mechanically during playback, as well as removing all real-time aspects of data retrieval off the CD. As Gunbei suggests, there would be no moving parts during playback which removes a whole raft of noise issues. I think Pls1's calculation of about 2 minutes to load a CD is about right which, while not ideal, certainly isn't out of the question considering the lengths most audiophiles are willing to go to better the sound of their system. -Kirk

dan2112
144 posts
 
This is a great idea and I am all for it!! Heck I'll even help write the software if I have time. However what about encrypted CDs and anti-piracy concerns? In the not distant future I think we can assume the RIAA will force us all to listen to encrypted CDs. There are CDs on the market today that are already watermarked. :-(

- Dan
blues_man
133 posts
 
As someone who designs Digital record and playback systems, I can tell you that this is done all the time, but for commercial applications. The problem is that for CD music, people want real-time playback. This just wouldn't be feasible for that. In addition the power required for refreshing the RAM would prohibit portable players. A better idea but one which also has drawbacks for real-time applications is to prefetch some fixed amount of data. Of course all of this is moot because even if you produce these transports, you'd have to redo the CD spec as it's designed for real-time reading and not bulk I-O.
kthomas OP
911 posts
 
I only envisioned this as a high-end application - hence, no need for portable players, etc., and an acceptance of the initial delay for the improved performance, since audiophiles are the type that are willing to go to these lengths. I'm not sure about the power requirements prohibiting portable players anyway, though - we already have portable MP3 players which are the same thing with compression, though the goal is ease of use and amount of music as opposed to better audio performance.

I'm definitely NOT a designer of digital recording and playback systems, but I've integrated lots of related but unconnected systems in my professional life. It would seem here that you already have a functional (and cheap!) design for reading a CD into RAM, and as others have noted, it's already incorporated into many high-end players to cache data in RAM and re-clock it out to the DAC. I don't want to over-trivialize it, but it seems like a little "glue" to put the two together would suffice.

I agree with everyone that in the "I want it NOW" environment we currently live, the loading delay would be unacceptable for a mass consumer version of this, even if it was cost-effective. -Kirk

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